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Title: Stretching Epitaxial La 0.6Sr 0.4CoO 3–δ for Fast Oxygen Reduction

Abstract

The slow kinetics of the oxygen reduction reaction (ORR) is one of the key challenges in developing high performance energy devices, such as solid oxide fuel cells. Straining a film by growing on a lattice-mismatched substrate has been a conventional approach to enhance the ORR activity. However, due to the limited choice of electrolyte substrates to alter the degree of strain, a systematic study in various materials has been a challenge. Here, we explore the strain modulation of the ORR kinetics by growing epitaxial La 0.6Sr 0.4CoO 3-δ (LSCO) films on yttria-stabilized zirconia substrates with the film thickness below and above the critical thickness for strain relaxation. Two orders of magnitude higher ORR kinetics is achieved in an ultrathin film with ~0.8% tensile strain as compared to unstrained films. Time-of-flight secondary ion mass spectrometry depth profiling confirms that the Sr surface segregation is not responsible for the enhanced ORR in strained films. Here, we attribute this enhancement of ORR kinetics to the increase in oxygen vacancy concentration in the tensile-strained LSCO film owing to the reduced activation barrier for oxygen surface exchange kinetics. Density functional theory calculations reveal an upshift of the oxygen 2p-band center relative to the Fermi levelmore » by tensile strain, indicating the origin of the enhanced ORR kinetics.« less

Authors:
ORCiD logo [1];  [2];  [3];  [4]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [3]; ORCiD logo [2]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Wisconsin - Madison, Madison, WI (United States)
  3. Univ. of South Carolina, Columbia, SC (United States)
  4. Univ. of Kentucky, Lexington, KY (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1414719
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 121; Journal Issue: 46
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Lee, Dongkyu, Jacobs, Ryan, Jee, Youngseok, Seo, Ambrose, Sohn, Changhee, Ievlev, Anton V., Ovchinnikova, Olga S., Huang, Kevin, Morgan, Dane, and Lee, Ho Nyung. Stretching Epitaxial La0.6Sr0.4CoO3–δ for Fast Oxygen Reduction. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.7b06374.
Lee, Dongkyu, Jacobs, Ryan, Jee, Youngseok, Seo, Ambrose, Sohn, Changhee, Ievlev, Anton V., Ovchinnikova, Olga S., Huang, Kevin, Morgan, Dane, & Lee, Ho Nyung. Stretching Epitaxial La0.6Sr0.4CoO3–δ for Fast Oxygen Reduction. United States. doi:10.1021/acs.jpcc.7b06374.
Lee, Dongkyu, Jacobs, Ryan, Jee, Youngseok, Seo, Ambrose, Sohn, Changhee, Ievlev, Anton V., Ovchinnikova, Olga S., Huang, Kevin, Morgan, Dane, and Lee, Ho Nyung. Tue . "Stretching Epitaxial La0.6Sr0.4CoO3–δ for Fast Oxygen Reduction". United States. doi:10.1021/acs.jpcc.7b06374.
@article{osti_1414719,
title = {Stretching Epitaxial La0.6Sr0.4CoO3–δ for Fast Oxygen Reduction},
author = {Lee, Dongkyu and Jacobs, Ryan and Jee, Youngseok and Seo, Ambrose and Sohn, Changhee and Ievlev, Anton V. and Ovchinnikova, Olga S. and Huang, Kevin and Morgan, Dane and Lee, Ho Nyung},
abstractNote = {The slow kinetics of the oxygen reduction reaction (ORR) is one of the key challenges in developing high performance energy devices, such as solid oxide fuel cells. Straining a film by growing on a lattice-mismatched substrate has been a conventional approach to enhance the ORR activity. However, due to the limited choice of electrolyte substrates to alter the degree of strain, a systematic study in various materials has been a challenge. Here, we explore the strain modulation of the ORR kinetics by growing epitaxial La0.6Sr0.4CoO3-δ (LSCO) films on yttria-stabilized zirconia substrates with the film thickness below and above the critical thickness for strain relaxation. Two orders of magnitude higher ORR kinetics is achieved in an ultrathin film with ~0.8% tensile strain as compared to unstrained films. Time-of-flight secondary ion mass spectrometry depth profiling confirms that the Sr surface segregation is not responsible for the enhanced ORR in strained films. Here, we attribute this enhancement of ORR kinetics to the increase in oxygen vacancy concentration in the tensile-strained LSCO film owing to the reduced activation barrier for oxygen surface exchange kinetics. Density functional theory calculations reveal an upshift of the oxygen 2p-band center relative to the Fermi level by tensile strain, indicating the origin of the enhanced ORR kinetics.},
doi = {10.1021/acs.jpcc.7b06374},
journal = {Journal of Physical Chemistry. C},
number = 46,
volume = 121,
place = {United States},
year = {Tue Oct 31 00:00:00 EDT 2017},
month = {Tue Oct 31 00:00:00 EDT 2017}
}